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38
result(s) for
"Rykalin, V. I."
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Searches for the light invisible axion-like particle in K+→π+π0a decay
A high-statistics data sample of the
K
+
decays is recorded by the OKA collaboration. A missing mass analysis is performed to search for a light invisible pseudoscalar axion-like particle (ALP)
a
in the decay
K
+
→
π
+
π
0
a
. No signal is observed, and the upper limits for the branching ratio of the decay are calculated. The
90
%
confidence level upper limit changes from
2.5
·
10
-
6
to
2
·
10
-
7
for the ALP mass from 0 to 200 MeV/
c
2
, except for the region of
π
0
mass, where the upper limit is
4.4
·
10
-
6
.
Journal Article
Observation of K+→π+π0π0γ decay
The
K
+
→
π
+
π
0
π
0
γ
decay is observed by the OKA collaboration. About 60 events of the decay observed with signal:noise
≈
1
. The branching ratio obtained by normalization to
K
+
→
π
+
π
0
π
0
is measured to be
(
3.7
±
0.9
(
s
t
a
t
)
±
0.3
(
s
y
s
t
)
)
×
10
-
6
for
E
γ
∗
>
10
MeV
. The branching ratio,
γ
energy spectrum and angular distribution are consistent with ChPT prediction.
Journal Article
Thin Scintillation Counters in Particle Detectors
The paper deals with the design and parameters of thin scintillation counters, not more than several mm thick, with a large geometric aperture. Such counters with high light yield and, accordingly, with high detection efficiency of charged particles are widely used in nuclear and particle physics, as well as in facilities for beta contamination monitoring of clothing and various objects by extracting signals of low-energy electrons against a background of gamma radiation. In these applications just the minimum thickness of the scintillator with the required large geometric dimensions of the detector determines the high efficiency of the counters.
Journal Article
Study of K+→π0e+νγ decay with OKA setup
Results of a study of the K+→π0e+νγ decay at OKA setup are presented. More than 32,000 events of this decay are observed. The differential spectra over the photon energy and the photon–electron opening angle in kaon rest frame are presented. The branching ratios, normalized to that of Ke3 decay are calculated for different cuts on Eγ∗ and cosΘeγ∗. In particular, the branching ratio for Eγ∗>30 MeV and Θeγ∗>20∘ is measured R = Br(K+→π0e+νeγ)Br(K+→π0e+νe) = = (0.587±0.010(stat.)±0.015(syst.))×10-2, which is in a good agreement with ChPT O(p4) calculations.
Journal Article
Studying Mechanisms of Hadron–Nuclear Interaction on Positive Beam Line 18 of the U-70 Accelerator
Abstact
—The paper presents the upgrade project of the Hyperon-M experiment in the positive beam line of the U-70 accelerator complex in Protvino to study hadron-nuclear interaction mechanisms. It is proposed that the setup be upgraded to study the excited states of secondary nuclei formed by different types of primary hadron–nuclear interaction using precision nuclear gamma-ray spectroscopy. This could open a new direction of the nuclear physics at the junction with the physics of elementary particles at intermediate energies.
Journal Article
Search for heavy neutrino in K + → μ + ν H decay
A high statistics data sample of the K+→μ+νμ decay was accumulated by the OKA experiment in 2012. The missing mass analysis was performed to search for the decay channel K+→μ+νH with a hypothetic stable heavy neutrino in the final state. The obtained missing mass spectrum does not show peaks that could be attributed to existence of stable heavy neutrinos in the mass range (270
Journal Article
Observation of$$K^{+} \\rightarrow \\pi ^{+}\\pi ^{0}\\pi ^{0}\\gamma $$decay
The$$K^{+} \\rightarrow \\pi ^{+}\\pi ^{0}\\pi ^{0}\\gamma $$K + → π + π 0 π 0 γ decay is observed by the OKA collaboration. About 60 events of the decay observed with signal:noise$$\\approx 1$$≈ 1 . The branching ratio obtained by normalization to$$K^{+} \\rightarrow \\pi ^{+}\\pi ^{0}\\pi ^{0}$$K + → π + π 0 π 0 is measured to be$$(3.7 \\pm 0.9(stat) \\pm 0.3(syst))\\times 10^{-6}$$( 3.7 ± 0.9 ( s t a t ) ± 0.3 ( s y s t ) ) × 10 - 6 for$$E_{\\gamma }^*>10\\,\\textrm{MeV}$$E γ ∗ > 10 MeV . The branching ratio,$$\\gamma $$γ energy spectrum and angular distribution are consistent with ChPT prediction.
Journal Article
Searches for the light invisible axion-like particle in$$K^{+} \\rightarrow \\pi ^{+}\\pi ^{0} a$$decay
A high-statistics data sample of the$$K^{+}$$K + decays is recorded by the OKA collaboration. A missing mass analysis is performed to search for a light invisible pseudoscalar axion-like particle (ALP) a in the decay$$K^{+} \\rightarrow \\pi ^{+} \\pi ^{0} a$$K + → π + π 0 a . No signal is observed, and the upper limits for the branching ratio of the decay are calculated. The$$90\\%$$90 % confidence level upper limit changes from$$2.5\\cdot 10^{-6}$$2.5 · 10 - 6 to$$2\\cdot 10^{-7}$$2 · 10 - 7 for the ALP mass from 0 to 200 MeV/$$c^{2}$$c 2 , except for the region of$$\\pi ^{0}$$π 0 mass, where the upper limit is$$4.4\\cdot 10^{-6}$$4.4 · 10 - 6 .
Journal Article
Application of a Thin Organic Scintillator to Study 3α Fragmentation of 12C Nuclei in Interactions with Relativistic Muons and Hadrons
The analysis of amplitude spectra from a thin polystyrene-based scintillation counter on muon-enriched and hadron beams of channel 18 of the U-70 accelerator complex in Protvino has been presented. On the basis of statistics of 150 million events on the Hyperon-M setup, the contribution of the
-fragmentation processes are highlighted and the cross sections of these processes on hadron and pion beams with a momentum of 7 GeV/
c
have been measured. In the future, the obtained result may be of interest for the method of analyzing the age of gas fields based on the concentration of helium in natural gas, the formation of which is possible in the reaction of
fragmentation of carbon nuclei in
interactions induced by high-energy cosmic muons.
Journal Article
Measurement of T-odd asymmetry in radiative K+ -> pi0 e+ nu gamma decay using OKA detector
The paper presents a measurement of the T-odd correlation in radiation decay \\boldmath \\(K^+ \\rightarrow \\pi^{0} e^{+} \\nu_{e} \\gamma \\) performed on the installation of the 101200 candidate events of the investigated decay were identified. Measured correlation \\(\\xi_{\\pi e \\gamma}\\) -is a mixed product of moments \\(e^{+}\\), \\(\\pi^{0}\\), \\(\\gamma\\) in the kaon rest system, normalized by \\(M^{3}_{K}\\). To assess the asymmetry of the distribution by \\(\\xi_{\\pi e \\gamma}\\) the value used is \\(A_{\\xi}= \\frac {N_{+}-N_{-}} {N_{+}+N_{-}}\\), where \\(N_{+(-)}\\) is the number of events with \\(\\xi\\) greater than (less than) zero. For the \\(A_{\\xi}\\) asymmetry, the value is obtained \\(A_{\\xi} = (+0.1 \\pm 3.9(\\)stat.\\() \\pm1.7(\\)syst.\\())\\times10^{-3}\\) or \\(|A_{\\xi}| < 5.4\\times10^{-3} (90\\%~ CL)\\)
Paper